Do not check if artifact is already installed

[larsewi]

The Mender Client used to check if the downloaded artifact was already installed in the past. However, this check was removed in mendersoftware/mender@1fb6223 as it prevents the use of the "Force update" option, allowing a device to take part in the same deployment twice. Today, all the "already-installed" logic is performed in the backend.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[joelguittet]

I wasn't aware of this detail, thanks for this and thanks for this pull request @larsewi, looks good ! Merging